i) Field of the Invention
The present invention relates to a magneto-optical disc control system and method for effectively handling blank check state blocks on a medium.
ii) Description of the Related Arts
Recently, attention has fallen on the use of a magneto-optical disc device as a new memory suitable for a highly computerized environment. This magneto-optical disc device has well-known characteristic features, for instance, a magnetic film as a recording medium is used and an optical head having a laser light as a light source is used as a recording head. Also, a non-contact high density recording can be performed and, since the recording medium is composed of the magnetic film, the recording information is erasable and can be repeatedly recorded.
In turn, as other magnetic recording media, a floppy disc or a hard disc are used, and usually these media are distributed after certain check data are written in. However, in case of the magneto-optical disc device, only erase processing is carried out and data writing is notperformed before distributing. Hence, almost all areas are in undetermined states (not "O" nor "1" state). This area where data has never been written is hereinafter referred to as "a blank check state block".
Accordingly, when a user uses these devices in a DOS (disk operating system) such as MS-DOS or the like, it is necessary to perform initialization by using a prepared initializing program to write a value such as "0" on the entire surface. However, since the magneto-optical disc device has a large capacity, it takes a long time such as 40 to 60 minutes for the initialization, which imposes a large load on the user. Further, with the capacity increase of the medium, the initialization time is inclined to increase, and thus it is considered that this will brings about an even bigger problem in the future.
The reason why the initialization is required will now be described.
In general, when use of a new recording medium is started, a usual operation is carried out as follows. That is, certain data are written at an initial time and then the written data are read out. However, depending on application programs (task programs), it may not be possible to perform a reading operation at the initial time, and in such a case, a measure should be considered.
Before the appearance of the magneto-optical disc device, floppy disc and hard disc were used as the storage medium. However, in the DOS for performing the control and operation of these devices or the user's application program, the program is designed on the supposition that "0" can be read out of the position accessed for reading at the initial time. When the value other than "0" is read out, since only a normal or abnormal message can be returned from the device, an error is adapted to be displayed regardless of its cause. Hence, even when the blank check state block is accessed for reading at the initial time by using the DOS or the application program, the error arises. Accordingly, conventionally, the initialization is required prior to the use of the device.
Further, another method can be considered, for example, the DOS or the application program is changed to another system which does not expect "0". However, the system expecting "0" as the value in the position firstly accessed for reading has been used for the almost all floppy discs and hard discs for a long time and this is the system giving actual results from a historical point of view. Hence, to change this system for the magneto-optical disc system is not realistic from a view point of compatibility.
As a result, when the conventional application program is used as it is, the initialization of the magneto-optical disc device must be always carried out, and thus it takes a long time for this operation before the user can actually utilize the device.